Metal reinforced cellulose ester photolithographic printing plates



Aug. 3, 1954 G. F. NADEAU ETAL 2,685,511

METAL REINFORCED CELLULOSE ESTER PHOTOLITHOGRAPHIC PRINTING PLATES Filed May 3, 1952 '4f'` r`SE/v5/T/ZED HYDRODZED SURFACE x x x "CELLULOSE m/ACETATE LAYER ,2/ 550B AYER ,0 V`A LUM/NUM FOIL 3 fsf/5 AYER F1 9'. 2 14 SENS/T12 ED HYDROLYZED SURICE l, 1 {j- CELLULOSE TR/ACEMTE LAYER vh l f-su AYER ,o /-ALuM/NUM Fo/L /su LAYER /CELLULOSE TR/ACE'ATE LAYER Fi g 3 ,6. SENS/T/ZED HYDROLYZED LAYER ,5 1 cELLl/LEACEmTE-l/TYRNELAYER ,7 CELLULOSE TR/ACETATE LAYER 2 SUB LAYER ALUM/NUM Fon.

,3 SUB LAYER 16, SEMSlT/ZED HYDRO/.YZED SURFACE ,5 1 1 ELLULGSE ACEMTE-Bl/TYRATE LAYER CELLULOSE TRMCETATE LAYER SUB LAYER ALUM/NUM FO/L SUB LAYER l2 cEL/ uLosE TRMCEMTE LA YER il ,5 CELLULOSE ACETTE'jBUTY/MT LAYER i l Gale F/Yadeaa (7eme/13B. Sfar/c l INVENToRs l Anya A631:

Patented Aug. 3, 1954 METAL REINFORCED CELLULOSE ESTER PHOTOLITHOGRAPHIC PRINTING PLATES Gale F. Nadeau and Clemens B. Starck, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application May 3, 1952, Serial No. 285,934

12 Claims.

This invention relates to the preparation of an improved light-sensitive photographic element and more particularly to such element protected against halation and free from dimensional and chemical instability and especially designed for use in making lithographie printing plates.

This application is a continuation-in-part oi our copending application Serial No. 173,378, filed July l2, 195i), now Patent No. 2,635,962 of April 21, 1953.

Printing plates of the photolithographic type are well known having been prepared previously, for example, from metal plates carrying lightsensitive colloid layers and from cellulose ester plates carrying similar light-sensitive stratum or layer. R. S. Colt, in United States Patent 2,448,861, dated September 7, 1948, describes a `method for preparing cellulose ester type printing plates according to which a surface hydrolyzed cellulose ester sheet is sensitized with a bichromate such as potassium bichromate, and after exposure under a design, the exposed area is removed with aqueous solutions of chlorites or hypochlortes such as, for example, sodium hypochlorite, thereby producing ink-receptive areas in the region of the exposure and ink-repellant areas, when moistened, in the region of the unexposed areas. It is highly desirable in a process of the above kind to include an antihalation layer and, following the usual practice in the art, it might appear that the antihalation layer coated on the rear surface of the sensitive plate would provide adequate protection from halation effects. However, it has been found that when such elements are subjected to alkaline hydrolysis by immersion methods to produce a stratum of hydrolyzed cellulose ester on the surface of the plate, the dye later tends to be removed in the process leaving the residual dye in uneven and mottled condition, as well as contaminating the hydrolysis bath with dyestuii. Another disadvantage of such elements is that While satisfactory as a printing plate for short runs, on continued running they tend to stretch and pull out from clamps of the type used on many small oset printing presses. Accordingly, such elements have been found to lack dimensional and chemical stability for precision registration on long continued runs.

While reinforcing materials such as thin metal foils have been proposed heretofore for reinforcing various cellulose ester photographic elements, all attempts to produce a highly satisfactory type of surface hydrolyzed and sensitized cellulose ester printing plate provided with a thin metal foil reinforcement have failed for one reason or another. For example, when thin metal foil is used as the reinforcing material, the usual binding pastes or cements tend to break down and allow the cellulose ester coat or sheet to pull away from the metal foil at the edges of the composite plate, especially when the composite element or plate is subjected to the action of aqueous caustic solutions in the step of forming the surface hydrolyzed layer or surface on the cellulose ester coating or sheet. Subsequent treatment by various processing solutions and by prolonged use of the finished printing plate in contact with printing inks caused a similar distortion or peeling at theY edges of the plate. Where the reinforcing metal foil is a desirable metal such as zinc or aluminum, the aqueous caustic hydrolyzing solution vigorously attacks and corrodes such metal foils. Protective coatings or bacliings commonly employed to protect metal surfaces, when applied to the exposed back surface of the metal foil of the above type of composite plate have been found impractical to use or ineffective in that the bonding of the metal to the cellulose ester or to the protective coating or backing does not hold as rmly as desired, or in that the protective coating or backing is etched or dissolved away under the hydrolyzing action of the caustic solution.

We have now found that excellent light-sensitive photographic elements designed for preparing lithographie printing plates, and especially elements which are protected against halation effects and intimately bonded to reinforcing metal foil, and which have none of the aforementioned disadvantages of dimensional instability and adverse susceptibility to processing solutions, can be prepared as described hereinafter.

It is, accordingly, an object of our invention t0 provide light-sensitive elements having dimensional and chemical stability, and more particularly such elements protected against halation, for use in making lithographie printing plates. A further object is to provide lithographie printing plates having dimensional and chemical stability. Another objeot is to provide novel processes for preparing such photographic elements and printing plates. Other objects will become apparent hereinafter.

ln the accompanying illustrative drawings Figs. 1 4, Fig. l is an enlarged, diagrammatic crosssectonal view of a light-sensitive photographic element comprising a thin aluminum foil having an outer layer on one side of cellulose triacetate.

Fig. 2 is similar to Fig. 1 but denotes an aluminum foil having outer layers on both sides of cellulose triacetate.

Fig. 3 is similar to Fig. lk but differs therefrom in that the aluminum foil has an outer layer on one side of cellulose acetate-butyrate.

Fig. 4 is similar to Fig. 3, but diers therefrom in that the aluminum foil has outer layers on both sides of cellulose acetate-butyrate.

In accordance with our invention, we prepare our new light-sensitive photographic elements of the surface hydrolyzed and sensitized cellulose organic acid estei` type in a number of modifications, wherein the reinforcing material is a metal foil of from 0.002-0-005-inch thickness, depending on what type and thickness of element is desired. One form of the invention comprises an element having an overall thickness of anproximately 0.005-inch and is prepared by bondu ing a coated layer from a solution or dope of a cellulose organic acid ester preferably containing an antihalation dye incorporated therein to a metal foil such as zinc, aluminum, etc., preferably aluminum foil, by means of an interlayer or sublayer coated on the foil comprising a resinous, thermoplastic material, the other side of the foil being protected against the hydrolyzing and processing solutions by a similar layer of a resinous, thermoplastic material coated thereon, curing the coated foil and subjecting it to a hydrolyzing bath, followed by sensitization of the resulting hydrolyzed outer surface of the cellulose or ganic ester layer with a suitable sensitizing agent. Another form of the invention having an overall thickness of approximately 0.905- inch and particularly free from curl is prepared as above, but the cellulose organic acid ester in solution or dope form is applied as a coating to both sides of the subbed metal foil and at least one of the resulting outer surfaces is hy drolyzed and sensitized. Mixtures of one or more cellulose organic esters can be used. A particularly valuable element is one wherein the hydrolyzed and sensitized outside layer is a cellulose acetate-butyrate. When this kind of layer is subjected to hydrolysis, sensitized, exposed under a pattern and developed, the small halftone dots obtained are much stronger and show greater resistance to removal by swabbing action with aqueous caustic during processing than is the case with elements wherein the outer layer is some other cellulose organic acid ester such as. for example, cellulose triacetate. However, the cellulose acetate-butyrate shows relatively poor adhesion to the subbing layer. Consequently, to obtain a good quality element having an outer surface of cellulose acetatebutyrate, the metal foil is first subbed as before, then coated with a solution of a different cellulose organic acid ester to give a relatively thin layer of the ester, :oreferably cellulose triacetate, and then overcoated with a relatively thicker layer of a solution of cellulose acetate-butyrate preferably containing the antihalation dye. element a layer of cellulose acetate-butyrate can be used for the hydrolyzed and sensitized surface or stratum and the other side of the foil can be a layer of any of the other cellulose organic acid esters, for example, a layer of cellulose tri acetate. The subbing, coating and hydrolysis processes lend themselves readily to continuous form of operations.

Suitable cellulose organic acid esters which we employ for preparing the above-described prod ucts of our invention are substantially fully esterified esters including cellulose acetate hav-n ing the maximum resistance to moisture and containing about ti3.5% by weight of acetyl groups, and other esters of equivalent acyl con- In this kind of composite tent such as cellulose Dropionate, cellulose butyrate, cellulose acetate-propionate, cellulose acetate-butyrate, etc. The preferred outer surface is cellulose acetate-butyrate wherein the proportions of acetyl to butyryl can vary over a wide range, for example, 8% Bu. and 38% acetyl to 29% Bu. and 29% acetyl but preferably We use cellulose acetate-butyrates containing 17.5% Bu. and 30% acetyl. As previously mentioned the cellulose organic esters are applied in solution or dope form in one or more volatile solvents such as methylene chloride, ethylene dichloride, acetone, mixtures of these with up to about 20% by weight of one 01' more lower alcohols such as ethanol, methanol, etc. The solutions or dcpes intended for coating an outer surface of approximately D.001inch thickness are adjusted to a concentration sufficient for this purpose which depends upon the characteristics of the particular cellulose ester, but generally a concentration of from 6-12% has been found ecacious. The antihalation dye is incorporated in such solutions. Where cellulose acetate-butyrate is used as the outer layer to be hydrolyzed and sensitized, the intermediate cellulose triacetate solution functions as a cement between the subbed metal foil and the layer of cellulose acetatebutyrate, and is made up in similar solvents in concentrations of about from 0.5-2% by weight of cellulose triacetate. The thickness of this intermediate layer in dried condition does not ordinarily exceed 0.0001inch, although much thicker layers can be used, if desired.

In the hydrolysis step, the outer cellulose ester surface of the composite reinforced foil is hydrolyzed 0n the surface to the predetermined depth always leaving a stratum of unhydrolyzed material. This is accomplished by simply immersing the cellulose ester coated metal foil for a few minutes in an aqueous alcoholic solution of a caustic alkali (e. g. sodium hydroxide, potassium hydroxide, lithium hydroxide, etc), followed by washing the hydrolyzed product with water, neutralizing residual alkali with weak acid solution such as l5% aqueous acetic acid. In the case where cellulose ester coatings are made to both sides of the metal foil, if desired, only one side need be hydrolyzed by simply applying the hydrolyzing solution to this side as by swab bing action, and the like. The concentration of the hydrolyzing solution can be varied to some extent, depending on the time of exposure, the temperature of the bath and the degree of hydrolysis desired. A suitable solution is 5% sodiuin hydroxide in equal parts of ethyl alcohol and water, which gives good hydrolyzing results at 70 C. in about 3-5 minutes exposure. By operating at 60 F., the time required is somewhat longer, whereas at 100 F. the required time is considerably shorter and more critical.

The sobbing solutions which give sublayers having satisfactory adhesion to metal foils, particularly to aluminum foil, and to layers of cellulose organic acid esters coated from the aforementioned solutions or clopes, particularly to layers of cellulose triacetate coated from such solutions, are the sobbing solutions prepared with interpolymers of various mixtures of vinyl chloride and vinyl acetate which contain .a small proportion of free carboxylic acid groups. A suitable subbing solution consists of 6% by weight of a ternary interpolyrner containing approximately 86% by Weight of vinyl chloride groups, 13% by weight of vinyl acetate groups and 1% by weight of na-unsaturated dicarboxylic acid groups such as maleic or fumarie acid groups, 45% by weight of butyl acetate and ll9% by weight of methylene chloride. In place of methylene chloride, other solvents in admixture with each other or with methylene chloride can be employed such as acetone, 1,4-dioxane, ethylene dichloride, etc. The concentration of the interpolyiner in solution can be varied from about 1-10%, but preferably an approximately 6% solution of the above interpolymer or of generally similar interpolymers can be employed.

The antihala'tion dye employed in the process of our invention is selected from those which absorb in the blue an-d ultraviolet regions of the spectrum, and which are compatible with the cellulose organic acid ester solutions used for providing the coated layer of cellulose ester over the subbed metal foil. The preferred dye (or mixture of dyes) is used in a concentration of about 0.5-3%, although considerable variation is possible.

Suitable sensitizers include compounds which like bichromate (e. g. ammonium bichromate, sodium bichromate, potassium bichromate, etc.) will quickly oxidize hydrolyzed cellulose organic acid est-ers, in the presence of blue or ultraviolet light transmitted by a 4design such as a line or half-tone negative, to an alkali-soluble state, and include other sensitizing compounds such as ferrie ammonium oxalate, which can be used in conjunction with a ferricyanide (e. g. potassium ferricyanide, etc.) and which is reducible to ierrous salt images in the presence of light, but which does not oxidize cellulose in the presence of light, so that is necessary in this case to use alkaline oxidizing solutions such as hydrogen peroxide in dilute aqueous alkali metal hydroxide (e. g. sodium hydroxide, potassium hydroxide, etc.) to effect removal of 'the hydrolyzed cellulose ester in the exposed area. For a detailed description of suitable sensitizers and subsequent development of the relief images, reference can be had to Kenyon and Unruh, U. S. Patent 2,548,537, dated April l0, 1951.

The following examples and cross-sectional drawings will serve to illustrate further our new halation-free and dimensionally and chemically stable, light-sensitive, photographic elements, and the manner for preparing the same.

Example 1 A light-sensitive photographic element designed for preparing a lithographie printing plate of approximately @.006-inch thickness was prepared by iirs't subbing an aluminum foil of 0.0045-inch thickness on both sides with a solution consisting of 6% of an interpolymeric resin containing 86% by Weight of vinyl chloride groups, 13 by weight of Vinyl acetate groups and 1% by weight of dibasic acid groups such as maleic or fumarie acid groups, in methylene chloride, drying the sublayer, and then coating a layer of cellulose acetate 'solution over one of the subbed surfaces of the chloroaniline, was incorporated in the cellulose acetate coating solution or dope in an amount equivalent to 1% based on the weight of the solution. After curing the subbed and coated foil, it was surface hydrolyzed on the side having the outer cellulose triacetate coating by passing the coated foil through 5% sodium hydroxide dissolved in equal parts of ethyl alcohol and water, the hydrolyzing time being approximately 3 minutes at a bath temperature of 76 F. The hydrolyzed coated foil was then passed through an acid stop bath consisting of 2% acetic acid in water, washed with fresh water and dried. By this treatment there was obtained a hydrolyzed stratum of cellulose triacetate of a thickness on the order of one micron. By varying the hydrolytic conditions, the thickness of the hydrolyzed stratum can be varied to about half ythickness or increased to twice or even three times the above iigure. The hydrolyzed composite foil produced as described remained perfectly flat, showed no tendency to peel, the antihalation dye in Ithe unaiected part of the cellulose triacetate layer remained of even shades, and the sandwichediii-aluminum foil was entirely unaiiect-ed by the hydrolysis treatment. In the case where the subbing solution is applied only to the side of the foil which is to be coated with the cellulose triacetate solution, then prior to the hydrolysis step the other face of the foil must be coated with a thin coating of resinous protective material such as the subbing solution to protect the metal from the etching action of the caustic hydrolyzing bath.

The hydrolyzed composite foil was then sensitized by treating the hydrolyzed surface with an aqueous solution of ammonium bichromate -lunder non-actinic light conditions, and the sensitized composite foil dried. The light-sensitive photographic element thus obtain-ed was then exposed under a suitable design such as a line or half-tone negative to actinic light, and developed to a relief image by lightly swabbing the exposed Surface with a 2% aqueous caustic soda solution. The brown image which had formed on exposure soon disappeared and the hydrolyzed cellulose triacetate was gradually removed from the exposed area. Following neutralization of the excess alkali with 2% aqueous acetic acid solution, it was found that the exposed .and developed areas readily received greasy printing inks, whereas the areas containing unexposed hydrolyzed cellulose triacetate, when moistened, repelled such inks. The dried product thus obtained was free from dimensional distortions and weaknesses and gave excellent results as a printing plate over an extended period of operation in a press. Other of the mentioned sensitizers can be used in the above example in place of the ammonium bichromate.

The light-sensitive photographic element prepared as described in the above example is shown in cross-section in Fig. l, wherein the cellulose triacetate layer H having an outer sensitized hydrolyzed stratum I4 and an antihalation dye incorporated therein, is iirmly bonded as shown to a thin aluminum foil l by means of a thin layer l2 of subbing compound which acts as an adhesive, and wherein the other side of the foil is protected with a layer I3 of the subbing compound or some other equivalent resin material which is unafected by the caustic hydrolyzing bath.

Example 2 A light-sensitive photographic element designed for preparing a lithographic printing plate of approximately 0.006-inch thickness was prepared by first subbing an aluminum foil of 0.003-inch lthickness on both sides with a solution consisting of 6% of an interpolymeric resin containing 86% by weight of vinyl chloride, 13% by weight of vinyl acetate and 1% by weight-of dibasic acid groups such as maleic or fumarie acid groups, in methylene chloride, drying the subbed foil and then overcoating it with a cellulose triacetate solution in such manner that there resulted an aluminum foil having on each side firmly bonded thereto a layer of cellulose triacetate of approximately 0.0015inch thickness. The coating solution consisted by weight of 8% of cellulose triacetate, 80% of methylene chloride, 7% of isopropyl alcohol and of ethylene chloride. An antihalation dye which absorbed light in the blue region of the spectrum such as described by J. B. Dickey, U. S. Patent 2,264,303, dated December 2, 1941, particularly p-nitrobenzene-azo--hydroxyethyl-o-chloroaniline, was incorporated in the cellulose triacetate coating solution in an amount equivalent to 1 based on the weight of the dope. After curing the double coated aluminum foil, it was subjected to hydrolysis by swabbing one of the coated surfaces with aqueous alcoholic caustic solution, followed by sensitization with ammonium bichromate, etc. following the procedure described in Example 1. The sensitized photographic element so produced was exposed through a suitable design to actinic light and the relief image developed. Excellent results were obtained with this printing plate on long extended operation in a printing press.

The light-sensitive photographic element prepared as described in the above Example 2 is shown in cross-section in Fig. 2, wherein cellulose triacetate layer II having an antihalation dye incorporated .therein and having an outer hydrolyzed sensitized stratum I4, is rmly bonded as shown to a thin aluminum foil I9 by means of a thin layer I2 of subbing compound which acts as an adhesive, and wherein the other side of the foil is similarly bonded by means of the subbing compound I2 to a layer of cellulose triacetate II which may or may not contain an antihalation dye.

Example 3 A light-sensitive photographic element designed for preparing a lithographie printing plate of approximately 0.006-inch thickness was prepared` by rst subbing :an almninum foil of 0.0045-inch thickness both sides with a solution consisting of 6% of an interpolymeric resin containing 36% by weight of vinyl chloride groups, 13% by weight of Vinyl acetate groups and 1% by weight of dibasic acid groups such as maleic or fumaric acid groups, in methylene chloride, drying the sub layer, then coating a thin layer of 1.5% solution of cellulose triacetate in methylene chloride over one of the subbed surfaces of the aluminum foil, drying the coated foil, and then overcoating the layer of cellulose triacetate with an 8% solution of cellulose acetate-butyrate (containing 30% acetyl groups and 17.5% butyryl groups) in a 90: 10 mixture of ethylene dichloride and methyl alcohol, and containing 0.15% of triphenyl phosphate as a plasticizer, 0.75% of an orange dye, p-nitrobenzeneazo--hydroxyethyl-o-chloroaniline and 1.0% of a yellow dye such as o-nitrop-chlorobenzeneazo-5,5dimethyl1,3- cyclohexadione, based on the weight of cellulose acetate-butyrate, in such manner that the dried layer of cellulose acetate-butyrate had approximately 0.001-inch thickness. After curing the double coated foil, the outer cellulose acetatebutyrate surface was hydrolyzed by passing the composite foil through 5% sodium hydroxide dissolved in equal parts of ethyl alcohol and water, the hydrolyzing time being approximately S minutes at a bath temperature of 70 F. The hydrolyzed foil was then passed through an acid stop bath consisting of 2% aqueous acetic acid, washed with fresh water and dried. By this treatment there was obtained a hydrolyzed stratum of cellulose acetate-butyrate on the order of one micron. By Varying the hydrolytic conditions, the thickness of the hydrolyzed stratum can be varied to about half thickness or increased to twice or even three times the above ligure. The hydrolyzed composite foil produced as described remained perfectly at, showed no tendency to peel, the antihalation dyes in the unaffected part of the cellulose acetate-butyrate layer remained of even shades, and the sandwiched-in-aluminum foil was entirely unaiected by the hydrolysis treatment. In the case where the subbing solution is applied only to the side of the foil which is to be coated with the cellulose organic acid esters, then prior to the hydrolysis step the other face of the foil must be coated with a thin coating of resinous protective material such as the subbing solution to protect the metal from being etched by the caustic hydrolyzing bath.

The hydrolyzed composite foil was then sensitized by treating the hydrolyzed surface with an aqueous solution of ammonium bichromate under non-actinic light conditions and the sensitized composite foil dried. The light-sensitive photographic element thus obtained was then exposed under a suitable design such as a line or halftone negative to actinic light, and developed to a relief image by lightly swabbing the exposed surface with a 2% aqueous caustic soda solution. The brown image which had formed on exposure soon disappeared and the hydrolyzed cellulose acetate-butyrate was gradually removed from the exposed area. The elevated portions of the relief image (unexposed areas) were more sharply defined and stronger than similar reliefs produced as described in Example 1. Following neutralization of the excess alkali with 2% aqueous acetic acid solution, it was found that the exposed and developed areas readily received greasy printing inks, whereas the areas containing unexposed hydrolyzed cellulose acetate-butyrate, when moistened, repelled such inks. The lithographic plate so produced was free from dimensional distortions and weaknesses even after long periods of operation, and its printing face gave superior printings and had much longer useful life period of operation than was found with similar plates having printing faces produced with other of the mentioned cellulose organic acid esters such as, for example, with cellulose triacetate printing faces.

The light-sensitive photographic element prepared as described in the above example is shown in cross-section in Fig. 3, wherein the cellulose acetate-butyrate layer I5 having an outer sensitized hydrolyzed stratum I6 and an antihalation dye incorporated therein, is firmly bonded as shown to a thin layer of cellulose triacetate I'I and this latter layer is in turn bonded rmly to a thin aluminum foil Ii! by means of a thin layer I2 of subbing compound, and wherein the other side of the aluminum foil is protected with a layer I3 of the subbing compound or some other equivalent resin material which is unaiiected by the caustic hydrolyzing bath.

Example 4 A light-sensitive photographic element designed for preparing a lithographie printing plate of approximately 0.006-inch thickness Was prepared by first subbing an aluminum foil of 0.003-inch thickness on both sides with a solution consisting of 6% of an interpolymeric resin containing 86% by Weight of vinyl chloride, 13% by weight of vinyl acetate and 1% by Weight of dibasic acid groups such as maleic or fumarie acid groups, in methylene chloride, drying the subbed foil and then coating a thin layer of 1.5% solution of cellulose triacetate in methylene chloride over both of the subbed surfaces, drying the coated foil, and then overcoating the layer of cellulose triacetate on each side of the foil With an 8 solution of cellulose acetate-butyrate (containing 30% acetyl groups and 17.5% butyryl groups) in a 90:10 mixture of ethylene dichloride and methyl alcohol, and containing 15% of triphenyl phosphate, 0.75% of an orange dye, p-nitrobenzeneazo--hydroxyethyl-o-chloroaniline, and 1.0% of a yellow dye, o-nitro-p-chlorobenzeneazo-5,5-dimethyl- 1,3-cyclohexadione, based on the weight of the cellulose acetate-butyrate, in such manner that each of the dried layers of cellulose acetatebutyrate had a thickness of approximately 0.001- inch. After curing, one of these surfaces was then hydrolyzed, sensitized, exposed, developed and dried as described in Example 3. The printing plate so produced had similarly good `properties as that described in Example 3.

The light-sensitive photographic element prepared as described in above Example 4, is shown in cross-section in Fig. 4, wherein cellulose acetate-butyrate layer i having an antihalation dye incorporated therein and having an outer hydrolyzed sensitized Stratum it, is firmly bonded as shown to a thin layer of cellulose triacetate il and this latter layer is in turn bonded rmly to a thin aluminum foil it by means of a thin layer l2 of suboing compound, and wherein the other side of the aluminum foil is similarly attached by means ofthin layers l2 and i to cellulose acetate-butyrate layer l5 Which may or may not contain an antihalation dye.

By proceeding as shown in the foregoing examples, other operable light-sensitive photographic elements can be prepared, for example, by replacing the outer layers of cellulose triacetate and cellulose acetate-butyrate with layers of cellulose propionate, cellulose butyrate or cellulose acetate-propionate. For some purposes it may be desirable to hydrolyze and sensitize both outer surfaces of elements such as those of Examples 2 and fl. The elements wherein cellulose acetatebutyrate is employed as the outer layer need not have the antihalation dye incorporated in the cellulose acetate-butyrate layer, since it is also practical to incorporate such antihalation dyes in the intermediate cellulose triacetate layer. However, the antihalation dye can also be incorporated in the sub layer of any of the lightsensitive photographic elements of our invention. Although the invention has been illustrated in all of the examples With elements containing an antihalation dye in one or more layers on the light-sensitive side of the element, it will be understood that elements of more limited application which contain no antihalation dye in any of the layers are also included in our invention.

lli

The coating technique employed for preparing the light-sensitive photographic elements of the invention is according to Well-established procedures for obtaining flat, smooth, bubble-free layers of the material to be coated. Generally, the solution or dope is coated at or slightly above room temperature and then cured at elevated temperatures, but substantially below the boiling point of the solvent. The actual coatings can be accomplished by immersion, by coating from a hopper with a coating knife arrangement, by extrusion or spraying methods.

What We claim is:

1. A light-sensitive photographic element comprising a metal foil and a coated layer of cellulose organic acid ester bonded together with an interlayer comprising a resinous interpolymer of vinyl chloride, vinyl acetate and an na-ethylenically unsaturated dicarboxylic acid adherent thereto, the said cellulose organic acid ester layer having a hydrolyzed stratum. on its outer surface sensitized with an agent selected from the class consisting of oxidants for cellulose in the presence of light and light-reducible ferrie salts incapable of oxidation of cellulose to the alkalisoluble state in the presence of light, and the said aluminum foil having the outer surface thereof covered with a layer of the said resinous interpolymer.

2. A light-sensitive photographic element comprising a metal foil and a coated layer of cellulose organic acid ester bonded together with an intel-layer comprising a resinous interpolymer of vinyl chloride, vinyl acetate and an na-ethylenically unsaturated dicarboxylic acid adherent thereto, and wherein at least one of said layers on the light-sensitive side of the foil contains an antihalation dye, the said cellulose organic acid ester layer having a hydrolyzed stratum on its outer surface sensitized with an agent selected from the class consisting of oxidants for cellulose in the presence of light and light-reducible ferric salts incapable of oxidation of cellulose to the alkali-soluble state in the presence of light, and the said aluminum foil having the outer surface thereof covered with a layer of the said resinous interpolymer.

3. A light-sensitive photographic element comprising an aluminum foil and a coated layer of cellulose triacetate bonded together with an interlayer comprising a resinous interpolymer of vinyl chloride, vinyl acetate and an na-ethylenically unsaturated dicarboxylic acid adherent thereto, the said cellulose triacetate layer containing an antihalation dye incorporated therein and having a hydrolyzed stratum on its outer surface sensitized With an agent selected from the class consisting of oxidants for cellulose in the presence of light and light-reducible ferrie salts incapable of oxidation of cellulose to the alkali-soluble state in the presence of light, and the said aluminum foil having the outer surface thereof covered with a layer or" the said resinous interpolymer.

4. A light-sensitive photographie element cornprising an aluminum foil and a coated layer of cellulose triacetate bonded together with an interlayer comprising a resinous interpolyiner of vinyl chloride, vinyl acetate and an @a-ethylenically unsaturated dicarboxylic acid adherent thereto, the said cellulose organic acid ester layer containing an antihalation dye incorporated therein and having a hydrolyzed stratum on its outer surface sensitized with an agent selected from the class consisting of oxidants for cellulose in the presence of light and light-reducible ferrie salts incapable of oxidation of cellulose to the alkali-soluble state in the presence of light, and the said aluminum foil having the outer surface thereof covered with a composite layer of the said resinous interpolymer adjacent to the foil and a layer of the said cellulose triacetate adhered thereover.

5. A light-sensitive photographic element comprising an aluminum foil and a coated layer of cellulose acetate-butyrate bonded together with one interlayer adjacent to the foil comprising a resinous interpolymer of vinyl chloride, vinyl acetate and an ,-ethylenically unsaturated dicarboxylic acid and a second interlayer comprising cellulose triacetate adjacent to the layer of cellulose acetate-butyrate, the said cellulose acetate-butyrate layer containing an antihalation dye incorporated therein and having a hydrolyzed stratum on its outer surface sensitized with an agent selected from the class consisting of oxidants for cellulose in the presence of light and light-reducible ferrie salts incapable of oxidation to the alkali-soluble state in the presence of light,

and the said aluminum foil having the outer surface thereof covered with a layer comprising the said resinous interpolymer.

6. A light-sensitive photographic element comprising an aluminum foil and a coated layer of cellulose acetate-butyrate bonded together with one interlayer adjacent to the foil comprising a resinous interpolymer of vinyl chloride, vinyl acetate and an ,-ethylenically unsaturated dicarboxylic acid and a second interlayer comprising cellulose triacetate adjacent to the layer of cellulose acetate-butyrate, the said cellulose acetate-butyrate layer containing an antihalation dye incorporated therein and having a hydrolyzed stratum on its outer surface sensitized With an agent selected from the class consisting of oxidants for cellulose in the presence of light and light-reducible ferric salts incapable of oxidation v to the alkali-soluble state in the presence of light,

and the said aluminum foil having the outer surface thereof covered with a thin layer of the said resinous interpolymer adjacent to the foil and a layer of the said cellulose acetate-butyrate adhered thereover.

7. A method for preparing a photographic element which comprises subcoating both sides of a acid, then coating one side or" said subcoated foil with a composition comprising cellulose triacetate and an antihalation dye, and hydrolyzing an outer stratum of the said overcoating of cellulose triacetate.

9. A method for preparing a photographic element which comprises subcoating both sides of an aluminum foil with a composition comprising an interpolymer of vinyl chloride, vinyl acetate and an a-ethylenically unsaturated dicarboxylic acid, then coating both sides of said subcoated foil with a composition comprising cellulose triacetate and an antihalation dye, and hydrolyzing an outer stratum of at least one of said coatings of cellulose triacetate.

l0. A method for preparing a photographic element which comprises subcoating both sides of an aluminum foil with a composition comprising an interpolymer of vinyl chloride, vinyl acetate and an -ethylenically unsaturated dicarboxylic acid, then coating one side or" said subcoated foil with a composition comprising cellulose triacetate, and then overcoating the layer of cellulose triacetate with a composition comprising cellulose acetate-butyrate and an antihalation dye, and hydrolyzing an outer stratum of the said cellulose acetate-butyrate.

11. A method for preparing a photographic element which comprises subcoating both sides of an aluminum foil with a composition comprising an interpolymer of vinyl chloride, vinyl acetate and an ,-ethylenically unsaturated dicarboxylic acid, then coating both sides of said subcoated foil with a composition comprising cellulose triacetate, and then overcoating both the layers of cellulose triacetate with a composition comprising cellulose acetate-butyrate and an antihalation dye, and hydrolyzing an outer stratum of at least one of said layers of cellulose acetate-butyrate.

12. A method of preparing a photographic element which comprises subcoating both sides of an aluminum foil With a composition comprising an antihalation dye and an interpolymer of vinyl chloride, vinyl acetate and an ,/S-ethylenically unsaturated dicarboxylic acid, then coating at least one side of the subcoated foil with a composition comprising cellulose organic acid ester and hydrolyzing the outer stratum of at least one of said coatings of cellulose organic acid ester.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,972,314 Rado Sept. 4, 1934 1,997,745 Renker Apr. 16, 1985 2,311,489 Toland et al Feb. 16, 1943 2,312,852 Toland et al Mar. 2, 1943 2,433,515 Johado Dec 30, 1947 2,544,237 Reese Mar. 6, 1951 n.,- hay, 

1. A LIGHT-SENSITIVE PHOTOGRAPHIC ELEMENT COMPRISING A METAL FOIL AND A COATED LAYER OF CELLULOSE ORGANIC ACID ESTER BONDED TOGETHER WITH AN INTERLAYER COMPRISING A RESINOUS INTERPOLYMER OF VINYL CHLORIDE, VINYL ACETATE AND AN A B-ETHYLENICALLY UNSATURATED DICARBOXYLIC ACID ADHERENT THERETO, THE SAID CELLULOSE ORGANIC ACID ESTER LAYER HAVING A HYDROLYZED STRATUM ON ITS OUTER SURFACE SENSITIZED WITH AN AGENT SELECTED FROM THE CLASS CONSISTING OF OXIDANTS FOR CELLULOSE IN THE PRESENCE OF LIGHT AND LIGHT-REDUCIBLE FERRIC SALTS INCAPABLE OF OXIDATION OF CELLULOSE TO THE ALKALISOLUBLE STATE IN THE PRESENCE OF LIGHT, AND THE SAID ALUMINUM FOIL HAVING THE OUTER SURFACE THEREOF COVERED WITH A LAYER OF THE SAID RESINOUS INTERPOLYMER. 